1. Field of the Invention
The present invention relates to a nonvolatile semiconductor memory device. For example, the present invention relates to an NAND flash memory.
2. Description of the Related Art
In designing a memory such as a nonvolatile semiconductor memory device, reduction of area, achievement of higher speed, and reduction of current consumption are universal problems. For example, in designing a row-system circuit in an NAND flash memory, it is preferable to find out an optimal solution not only for the row-system circuit but also for an overall system including a pump serving as a voltage-supply source to the row system.
In a conventional NAND flash memory, a power line to supply a voltage for block decode to row decoders and a signal line to supply a voltage to word lines are arranged in a row-decoder array provided on one side of a memory-cell array. The power line and the signal line are not divided on the one side of the memory-cell array, but are shared by all the row decoders provided on the one side of the memory-cell array.
However, when the power line and the signal line are shared by all the row decoders, the load capacity of the pump circuit increases to supply source to the power line or the signal line, and the stress on the switching circuit (driver) increases to transfer the voltage to the power line or the signal line (see, for example, Japanese Patent Application Publication No. 2005-100538).